Unlike a blood test that provides information about stress hormone levels at a single point in time, analysis of a strand of hair can reveal trends in levels of the stress hormone cortisol over several months, according to the researchers.

The study, published April 17 in the Journal of Clinical Endocrinology & Metabolism, found that seniors with higher long-term levels of cortisol were more likely to have heart disease.

"Like high blood pressure or abdominal fat, the findings suggest elevated cortisol levels are an important signal that an individual is at risk of cardiovascular disease," study co-lead author Dr. Laura Manenschijn, of Erasmus Medical Center in the Netherlands, said in a news release from the Endocrine Society.

"Because scalp hair can capture information about how cortisol levels have changed over time, hair analysis gives us a better tool for evaluating that risk," she explained.

The researchers analyzed 1.2-inch samples of hair from the heads of 283 people, aged 65 to 85, and determined the participants' cortisol levels over the previous three months.

"The data showed a clear link between chronically elevated cortisol levels and cardiovascular disease," the other lead author, Dr. Elisabeth van Rossum, of Erasmus Medical Center, said in the news release. "Additional studies are needed to explore the role of long-term cortisol measurement as a cardiovascular disease predictor and how it can be used to inform new treatment or prevention strategies," she said.

The research suggested a link between stress hormone levels and heart risks. It didn't prove cause-and-effect.